Answer:
d = Â -26 mm
Explanation:
given,
initial position of paramecium, x = 65 mm
final position of paramecium, y = 39 mm
displacement of the paramecium's = ?
displacement  = final position - initial position
 d =  y - x           Â
d = 39 - 65 Â Â Â Â Â Â Â Â
d =  -26 mm       Â
The paramecium's displacement comes out to be -26 mm